Terahertz signals refer to signals in the terahertz range and the sub-terahertz range (e.g. signals having a frequency of about 100 GHz to 3 THz) lies between the infrared range and the microwave range. Until recently the terahertz range (including the sub-terahertz range) was widely ignored. Since there were few sources, applications and detectors for handling such signals. In recent years the terahertz range has begun to be explored, however the devices used for detecting terahertz electromagnetic signals generally use complex and expensive equipment, in contrast to simple, low cost CMOS integrated circuits used for other ranges. Additionally, some devices need to be cooled to function properly in contrast to CMOS integrated circuits, which can function at room temperature.
One of the problems with terahertz waves is that they penetrate many of the commonly used materials (e.g. materials used in CMOS technology), optionally, interfering with any accepted signals. Additionally, the strength of a signal accepted by a terahertz antenna is not much greater than the internal noise of a standard CMOS transistor.
Accordingly, it is desirable to design a terahertz sensor that can be implemented with standard CMOS technology and that provides a good quality output signal.